Variable dash expansion doesn't work in some cases
This work is done on a test virtual machine
In my / root directory I created the following:
"/ Root / Foo"
"/ Root / bar"
"/ root / i has multiple words"
Here is the (relevant) code I currently have
if [ ! -z "$BACKUP_EXCLUDE_LIST" ]
then
TEMPIFS=$IFS
IFS=:
for dir in $BACKUP_EXCLUDE_LIST
do
if [ -e "$3/$dir" ] # $3 is the backup source
then
BACKUP_EXCLUDE_PARAMS="$BACKUP_EXCLUDE_PARAMS --exclude='$dir'"
fi
done
IFS=$TEMPIFS
fi
tar $BACKUP_EXCLUDE_PARAMS -cpzf $BACKUP_PATH/$BACKUP_BASENAME.tar.gz -C $BACKUP_SOURCE_DIR $BACKUP_SOURCE_TARGET
This is what happens when I run my script with sh -x
+ IFS=:
+ [ -e /root/foo ]
+ BACKUP_EXCLUDE_PARAMS= --exclude='foo'
+ [ -e /root/bar ]
+ BACKUP_EXCLUDE_PARAMS= --exclude='foo' --exclude='bar'
+ [ -e /root/i have multiple words ]
+ BACKUP_EXCLUDE_PARAMS= --exclude='foo' --exclude='bar' --exclude='i have multiple words'
+ IFS=
# So far so good
+ tar --exclude='foo' --exclude='bar' --exclude='i have multiple words' -cpzf /backup/root/daily/root_20130131.071056.tar.gz -C / root
tar: have: Cannot stat: No such file or directory
tar: multiple: Cannot stat: No such file or directory
tar: words': Cannot stat: No such file or directory
tar: Exiting with failure status due to previous errors
# WHY? :(
Verification succeeds but --exclude='i have multiple words'
does not work.
Keep in mind that it works when I manually type it in my shell:
tar --exclude='i have multiple words' -cf /somefile.tar.gz /root
I know this will work in bash when using arrays, but I want it to be POSIX.
Is there a solution for this?
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Let's consider these scripts; ("with spaces" and "example.desktop" are sample files)
#!/bin/bash
arr=("with whitespace" "examples.desktop")
for file in ${arr[@]}
do
ls $file
done
It outputs exactly the same as yours;
21:06 ~ $ bash test.sh
ls: cannot access with: No such file or directory
ls: cannot access whitespace: No such file or directory
examples.desktop
You can set IFS with '\ n' to avoid spaces in filenames.
#!/bin/bash
arr=("with whitespace" "examples.desktop")
(IFS=$'\n';
for file in ${arr[@]}
do
ls $file
done
)
the output of the second version should be:
21:06 ~ $ bash test.sh
with whitespace
examples.desktop
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David H. of the LinuxQuestions forums pointed me in the right direction.
First of all, in my question, I did not use IFS =: until the end until the tar command Second, I included "set -f" for security
BACKUP_EXCLUDE_LIST="foo:bar:i have multiple words"
# Grouping our parameters
if [ ! -z "$BACKUP_EXCLUDE_LIST" ]
then
IFS=: # Here we set our temp $IFS
set -f # Disable globbing
for dir in $BACKUP_EXCLUDE_LIST
do
if [ -e "$3/$dir" ] # $3 is the directory that contains the directories defined in $BACKUP_EXCLUDE_LIST
then
BACKUP_EXCLUDE_PARAMS="$BACKUP_EXCLUDE_PARAMS:--exclude=$dir"
fi
done
fi
# We are ready to tar
tar $BACKUP_EXCLUDE_PARAMS \
-cpzf "$BACKUP_PATH/$BACKUP_BASENAME.tar.gz" \
-C "$BACKUP_SOURCE_DIR" \
"$BACKUP_SOURCE_TARGET"
unset IFS # our custom IFS has done it job. Let unset it!
set +f # Globbing is back on
I do not recommend using the TEMPIFS variable as I did, because this method does not set IFS correctly. Your best bet is to disable IFS when you're done with it.
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